What Is an Electronic Throttle Body?
Since basically their inception, vehicles with internal combustion engines have relied on a device to control the throttle and amount of air (and at one time, fuel) entering the vehicle. For nearly a century, this was controlled by a carburetor, allowing air to enter and mix with fuel, while throttle was controlled via a rod or cable. For nearly 30 years, fuel injected vehicles used a mechanical throttle body which controlled air intake and throttle by a manual lever and linkage assembly, similar to a carburetor. That is no longer the case for most vehicles on the road today. Instead, an electronic throttle body gets the job done. You may also hear an ETB called a drive-by-wire or throttle-by-wire system because the throttle is controlled electronically with no manual linkages.
What Does an Electronic Throttle Body Do?
Located between the intake manifold and the intake assembly, the throttle body controls how much air your vehicle’s engine receives based on how far you press the gas pedal. Generally, more airflow means more power. With an ETB, a small electric motor opens and closes the throttle body plate. As you may suspect, a computer controls the ETB. Depending on which vehicle you drive, this computer may either be the engine or powertrain control module, or a dedicated ETB module.
- Engine control modules (ECM) are computers that control the engine
- Powertrain control modules (PCM) control both the engine and the transmission
- ETB modules control the electronic throttle body
In drive-by-wire vehicles that do not have a ETB module, the electronic throttle body is controlled by either the ECM or PCM.
Vehicles made after the mid-2000s tend to have ETBs. Those that do typically have lower emissions and better fuel economy.
How Does an Electronic Throttle Body Work?
Most ETBs are simple devices that have four primary parts:
- A control module that serves as the nerve center for the ETB
- A motor that powers the mechanism
- A valve that opens and closes
- An accelerator pedal module that includes sensors
To function, the ETB requires information from a variety of systems. Your vehicle’s cruise control, accelerator, engine speed sensor, mass airflow sensor, and speed sensor communicate information to its engine control module. The module then determines how much to open the ETB’s valve. This, in turn, regulates how much air and fuel your vehicle’s engine receives. ETB’s are crucial with today’s technology of vehicles with adaptive cruise control, and other luxuries and safety features that allow the vehicles computer system to adapt to different driving conditions and situations.
Benefits of an ETB
Modern technology is not always better than its predecessors. Still, there are a number of advantages to driving a car with drive-by-wire technology:
- Less weight. Mechanical devices often weigh more than their electronic counterparts. This is generally true with ETBs. Because lighter cars usually use less fuel, you may achieve better fuel economy with a car that has an ETB over one with a manual throttle body
- Reliability. Mechanical components have moving parts that may wear out over time. With an ETB, you are apt to worry less about having an important component degrade or break completely
- Smoothness. ETBs often contribute to overall ride quality. That is, when you accelerate, your vehicle’s engine and transmission work together. The process, though, can be a bit choppy. The ETB helps smooth out your ride
Drawbacks of an ETB
Even though ETBs have a variety of benefits, they also have drawbacks:
- Corrosion. Some styles of ETBs have a potentiometer design. To function, these ETBs use a brush-and-rotor system that may corrode over time. Further, dirt, dust, and other debris may work its way into your vehicle’s ETB, causing a variety of performance issues
- Failure. Other types of ETBs have Hall-effect sensors. While these ETBs generally do not corrode, they are also not invincible. If your Hall-effect ETB is about to fail, you may not receive a warning. Instead of causing performance problems, these ETBs often simply quit
- Maintenance. Like with many other electronic components, ETBs are typically more difficult to maintain. If you want to service your vehicle’s ETB, you may need professional assistance. You may also have to flash reset your vehicle’s control module
- Diagnostics. Finally, diagnosing problems with an ETB may be more challenging than troubleshooting manual systems. That is, several trouble codes may implicate the ETB. Tracking down the source of the problem may require both time and patience
You may remember that some Toyota vehicles had problems with ETBs in the past. In some models, a faulty ETB led to uncontrollable acceleration. Fortunately, this problem seems to have resolved in recent years. In fact, there have been virtually no reports in the last few years of unchecked acceleration due to bad ETBs in Toyotas or other types of vehicles.
Generally, before your electronic throttle body fails completely, your vehicle will warn you of problems with the mechanism. Here are five warning signs your ETB may require some work:
Check Engine Light is On
Your vehicle’s control module keeps tabs on its ETB. If there is a problem with its functionality or performance, you are apt to see a light appear on your dashboard.
Engine Does Not Idle Correctly
Because the air entering your vehicle’s engine plays an important role in idling, your car may begin to run roughly. Alternatively, your engine’s normal idle speed may increase.
If your vehicle’s engine does not have the correct amount of air flowing into it, your car may stall, or its engine may die.
Car Loses Power
Internal combustion engines require a steady supply of both air and fuel to operate normally. If your ETB is not supplying adequate air, your car may lose power. You may also notice a decrease in fuel economy.
Car Goes into Limp Mode
Many modern vehicles have a failsafe called limp mode. To protect the engine from damage, these vehicles reduce power, allowing you to drive home at a slow speed. A bad ETB can encourage your car to go into limp mode.
With time, carbon and other contaminants may begin to accumulate inside your vehicle’s ETB. While most vehicle manufacturers do not include routine ETB maintenance in their service schedules, having your system cleaned periodically may be a smart idea. Note, though, that some vehicles must relearn idle speed after an ETB cleaning.
As you can see, on many vehicles, the electronic throttle body is an essential component that performs a valuable service. While you may be able to mostly ignore your vehicle’s ETB, you should understand what it does. You should also recognize the warning signs of a failing part. Regardless, when servicing your system, always choose top-grade components from reliable manufacturers.